Unfortunately Canada is not the land of eternal snow, as many Americans think - at least not the Canada that's accessible within 10 hrs of Connecticut! For year-round snow in Eastern Canada, you have to go a long way north to mountains with no road access and no commercial ski operations. Montreal, which is surrounded by good skihills, has summers averaging only a couple of degrees cooler than Connecticut. It's warm/ hot and humid. The mountains in eastern Canada are not that high, so the temperature variable between the valleys and the peaks (Say between Montreal and the peak of Mt-Tremblant at only 900m) is nowhere near as great as in the west (Say, between Portland and the peak of Mt Hood at 3400m). Most places are shut down by mid-April, even places in northern Quebec, like Le Massif. Even most of the peaks have lost their snow by early June or earlier, and by that time it's full hiking season.
Your best bet for late-season is on home soil in northern VT and NH. Stowe is open into early May I believe and Killington is sometimes open as late as early June. I can't vouch for the conditions at this time however! There is always the 'back-country' experience of Tuckerman's Ravine on the side of Mt Washington in New Hampshire. You have to hike to the ravine, but because it's usually out of the sun, and on the highest mountain in the northeast, the snow sticks around a LONG time. From what I'm told you can do the ravine well into summer, but you have to work for it! I hiked a little in the area in August a couple of years back and there were still large patches of snow in the ravine then. I think it's pretty reliable until late May or so, but don't quote me on that.